The present invention relates to trigger valves, and particularly to a trigger valve for use in a pneumatic nail gun. The trigger valve installs a valve bar mechanism, which is capable of being pressed and released.
In general, a trigger with a trigger valve is installed in a gun body of a pneumatic nail gun, adjacent to an end of a compressed air chamber of the pneumatic nail gun. The user can press the trigger to actuate a valve bar in the trigger valve to upwardly move, for guiding the compressed high pressure air to drive a piston to hit nails. The user also can release the trigger to actuate the valve bar to downwardly move to reposit, for guiding the compressed high pressure air to drive the piston to reposit.
A valve bar of a conventional trigger valve includes an upper bar portion nesting the main body of the valve bar, and a bottom bar portion extended out of the trigger valve for being abutted by the trigger. The trigger valve also includes an air tight ring surrounding the upper bar portion, to form a valve stopper, for switching a passage in the states of guiding the high pressure air into the valve, or exhausting the high pressure air. The trigger valve further includes a spring disposed at the upper bar portion, for driving the valve bar to downwardly move to reposit while the trigger being released. The related arts, such as JP Patent No. 08-025245 and JP Patent No. 08-090449 respectively disclosed a typical trigger valve, in which, a valve stopper with larger diameter is integrated with a valve bar, for switching a passage of an air chamber in the trigger valve. Another related art, such as JP Patent No. 09-168976 also disclosed a trigger valve, the valve bar of which formed a ring portion with larger diameter, for abutting and supporting a spring. However, the way of increasing the diameter of the upper portion of the valve bar makes it harder when the user presses the trigger to actuate the valve bar to upwardly move.
Moreover, JP Patent No. 2005-262381 disclosed a valve bar formed a ring portion with larger diameter, for supporting and abutting a spring. The valve bar further nested a moveable valve stopper to switch a passage in the states of guiding the high pressure air into the valve, or exhausting the high pressure air. However, the valve stopper moves in a direction reverse to that of the valve bar during the processes of pressing and releasing the valve bar. That is, besides the problem of harder operation, air barrier is liable to generate between against surfaces of the valve bar and the valve stopper during the processes of pressing and releasing the valve bar. In addition, the high pressure air in the trigger valve cannot assist in overcome the resistance of the valve bar in upwardly/downwardly moving process, which impact the reliability of the operation of the nail gun installed this trigger valve.
Accordingly, what is needed is a trigger valve for pneumatic nail gun that can overcome the above-described deficiencies.